Mass selection in breeding: examples

Selection is a science that derives new varieties of plants, breeds of animals, microorganisms. The main criterion for choosing a new, better material is individual and mass selection as a breeding method.

Typically, breeding is done by crossing and mutating the genes of the parent specimens, and then artificial selection is performed . All new breeds, varieties, strains created by man have certain morphological and physiological properties. Each species is adapted for certain climatic zones. All the new items are checked, compared with other grades at special stations.

Mass method of selection of plants

Mass selection in the breeding of new varieties of plants provides for pollination at once a large number of plants. Most often this method is used for breeding new varieties of rye, maize, sunflower, wheat. With the screening of these crops, new varieties consist of heterozygous species and have a unique genotype.

Mass selection in breeding allows obtaining new varieties with improved qualities. However, this method is considered unstable because of the high probability of unplanned cross pollination (insects, birds).

Mass selection of plants is the definition of a group of plant specimens, similar to each other according to established characteristics. For example, you can take the method of breeding a new generation of cereals. Usually the production of varieties by a mass method of breeding presupposes the sowing of a large number of specimens with further evaluation of their development and growth, resistance to diseases, pests. Also, the level of precocity, climate requirements, yields is estimated. When breeding new rye varieties, only those specimens of plants that are more resistant to various impacts and having a large ear with the greatest number of grains are selected by breeders. When re-sowing the received material, only those species of plants that have shown themselves on the best side are again selected. As a result of this work, a new variety, with homogeneous genes, is obtained. This is the mass selection. Examples of rye selection show how plants are selected.

Mass selection has many advantages, among which the simplicity, economy and the ability to get new varieties of plants in a short time are considered to be the main ones. The shortcomings include the inability to obtain a detailed evaluation of the offspring.

The effectiveness of mass selection

When working with self-pollinators and crossovers, mass selection is used as a breeding method. Its effectiveness depends on the gene, heredity, the size of the sample selected.

If the genes responsible for the signs have stable signs, then the selection result will be high.

When plants inherit the desired characteristics, selection is terminated, the variety is given a name. With poor indicators, the selection process continues. It lasts until the breeders get all the desired results for yield, fruit size, resistance to harmful factors, pests, diseases. And with mass selection, sometimes the previously selected offspring differs from the following, taken from parents with poor indicators.

For successful breeding work, the value of the sample is important. If a material with low indices is taken, then the plant may display inbreeding depression, which reduces the yield.

Mass selection is most effective when combined with additional selection methods. Most often it is used in conjunction with hybridization, polyploid method of plant breeding.

Hybridization

Hybrid - a plant of the first generation, which has increased viability and higher productivity in comparison with parental forms. With further use of seeds of hybrids, the genes laid by parents are destroyed.

Polyploid selection

The method of polyploidy also refers to hybrid. When creating new varieties, breeders use polyploidy, which leads to an increase in the size of plant cells and multiplication of chromosomes.

A large number of chromosomes increases the resistance of the plant to various diseases and various adverse factors. If several chromosomes are damaged in plants, the others remain unchanged. All plants obtained by the polyploid selection method have excellent viability.

Examples of mass selections

An example of obtaining a hybrid by mass selection is triticale. This plant was obtained by crossing wheat and rye. The new variety has a high frost resistance, unpretentious and resistant to many diseases.

The Russian academician received new wheat-grass varieties of plants, which are highly resistant to lodging. However, the first plants were not suitable for obtaining planting material, since their genome contained different chromosomes that did not participate in meiosis. In further studies, it was proposed to double the number of certain chromosomes. The result of the work was the amphidiploid.

Breeders crossed cabbage with radishes. In these plants, the number of chromosomes is identical. The last result carried 18 chromosomes, but it was infertile. Subsequent doubling of the number of chromosomes led to a plant with 36 chromosomes and having fruits. The resulting organism had signs of cabbage and radishes.

Another example of hybridization is corn. It was she who became the ancestor of heterotic hybrids. The yield indicator of the hybrid culture was higher by thirty percent than that of the parents.

Conclusion

When a new line appears, only clean plants are selected. The most successful combinations of hybrids are determined during the experiments. The results are recorded and used for further production of hybrid crops.

The breeding of new varieties, which are obtained only by mass selection, made it possible to obtain high-yield varieties of wheat, rice, maize, rye. An example of such works are varieties bred by Russian breeders. These are grains "Saratov-29", "Saratov-36", "Bezostaya-1", "Aurora". They are resistant to lodging, they practically do not get sick, they can produce a stable crop in any climatic conditions.